That's a remaining mystery in the continuing saga of the rumors about Baltimore Mayor Martin O'Malley's marriage and the role of a former Ehrlich administration staffer in spreading them.

A week ago, Washington Post political reporter Matthew Mosk confronted Joseph F. Steffen Jr., a longtime congressional office worker for Gov. Robert L. Ehrlich Jr., asking him if he used the name NCPAC - an acronym for National Conservative Political Action Committee - in postings about the rumors on the conservative Web message board www.FreeRepublic.com.

Steffen, a former staffer with the committee, known for its aggressive tactics in Senate campaigns, acknowledged that was his name on the Web site. Within hours, Ehrlich had denounced the messages, disclaimed any knowledge that they were being spread and asked for Steffen's resignation. The aide agreed.

As NCPAC, Steffen posted messages and conducted private exchanges with other FReepers, as denizens of the site call themselves, about rumors that O'Malley cheated on his wife.

The most damaging comments were made in an exchange with the mysterious MD4BUSH, a FReeper whose identity remains unknown.

Steffen is hardly the first to refer to the rumors. As has been pointed out by FReepers, Ehrlich and many others, the stories existed long before NCPAC's first reference to them in October.

Indeed, Steffen had scores of Internet posts on dozens of topics. Here's how one FReeper, named "GOP 1900_AD," describes them:

"I analyzed a year's worth of NCPAC's posts. Indeed, by FR standards, I consider him quite mild. What I would say, and please, no offense to Mr. Steffen, is that there was a certain folksy, almost naive charm to them. He is a very real and warm person. The mistake, if any, was that he was a bit too open about who he worked for. ... It was a case of guilt by association, with no evidence whatever of conspiracy or ill intent."

On the FreeRepublic site, many posters believe Steffen was the victim of a sting operation, enticed into talking about the O'Malley rumors by MD4BUSH, whom they suspect is a Democratic operative, a Washington Post reporter, an O'Malley ally or an enemy of Steffen's posing as a rock-ribbed conservative.

According to a member profile on the Web site, MD4BUSH joined the online community on Oct. 7, 2004, and gave this description of him- or herself: "I hate John Kerry and I'm sick of his lies. This is the most important election in history and George Bush must win. If not the Islamic Terrorists will win, there will be more attacks on the states."

Freepers say this description is a little thin compared with other contributors to the site, and that MD4BUSH was a johnny-come-lately to the site.

A little more than a week later, MD4BUSH was exchanging messages with NCPAC, hinting that he or she wanted to talk about state politics.

"We gotta be real about 2006 gonna be tough. Might need to play dirty," MD4BUSH wrote to NCPAC.

Soon the topic turned to the O'Malley rumors, with NCPAC acknowledging that some dirty play was underway.

"As for MO'M, [an apparent reference to O'Malley] his day is coming. A lot of the reason that everyone knows his history is because of what has gone on beneath the surface," NCPAC wrote to MD4BUSH on Oct. 18 in a private exchange between site contributors known as FReepmail. A day later, he wrote: "A few folks put in a lot of effort to ensure the MO'M story got some real float."

Ehrlich has denied knowing about Steffen's activities, and Steffen, who apologized to O'Malley last week, has not implicated his former boss.

But as Mosk was bringing the story to fruition, a curious thing happened. Just minutes after the Post published the story on its Web site last Tuesday, MD4BUSH gathered all the exchanges from NCPAC and posted them in a convenient place on the Web site. MD4BUSH even underlined the juiciest parts. . Even semi-skilled and out-of-touch newspaper reporters - whom FReepers refer to as MSM, or mainstream media, and they don't like us "lurking" on their site, thank you very much - would have no trouble finding them.

That fact alone seems to demonstrate that MD4BUSH had close knowledge of the schedule and activities of at least one newspaper reporter working to smoke out Steffen.

Last Friday, the head of the Web site, Jim Robinson, posted: "I've got some very interesting information for the governor's investigation regarding the Maryland Democrat Party dirty trickster that setup Steffen and the Washington Post reporter, Democrat operative that was working in concert with him. Almost hoping to receive a subpoena."

State Democratic Party officials insist they do not know the identity of MD4BUSH.

For now, MD4BUSH will remain one of Maryland's great unsolved political questions.